I made this post in reply to a similar request at the UK Forum, here it is again in case you didn't see it:
I tried this strat method with my D. acturi. Seeds were sown on wet live sphagnum and placed in the fridge for about 3 months, and then were put in the freezer for another 2 weeks. The pots were then brought into cultivation around Feb. Nothing happened. Hmmmph. So I figured what do I have to lose. I then put the pots outside with shelter from overhead rain. In my conditions, Feb. remains frozen. Around mid-April when the freeze was over I again checked the pots. Nothing doing there. At this stage I pretty much gave up, but upon rediscovering the pots in early June, now nearly bone dry, I found the seed had germinated. Not well, but there were seedlings. I am amazed that they were growing in such dry conditions! From all this I conclude that a long strat is definitely needed, and feel that sowing the seed in September for germination in June is probably a good bet. I would split the difference in time between the fridge and the freezer, and put the plants outside in June. This will be my approach with D. stenopetala and D. uniflora as well, if I ever am fortunate to get the seed again. The seed I sowed was over 2 years old by the way. It goes to show this seed has a long period of viability. I wish you the best success with your attempt, and please post your results or lack of them! Many thanks!